{{ $currentPage := . }}
<header>
  <h1>
  {{ with resources.Get "img/titre.png" }}
    <a href="{{ $.Site.BaseURL | relURL }}">
      <img src="{{ .RelPermalink }}" />
    </a>
  {{ else }}
      <a href="{{ $.Site.BaseURL | relURL }}">{{ .Site.Title }}</a>
  {{ end }}
  </h1>
  {{ with $.Site.Params.Description }}
    {{ . }}
  {{ end }}
  <nav>
    {{ range $.Site.Sections }}
      <a href="{{ .Permalink }}" class="{{ if eq $currentPage.Section .Section }}exposed{{ end }}">
        {{ .Title | markdownify }}
      </a>
    {{ end }}
  </nav>
</header>